The present invention is directed to an adhesive tape formed from a vibration damping composition, and more particularly, to a vibration damping composition which can be extruded into the form of a self-adhesive vibration damping tape for use in automotive, appliance and other applications.
Vibration damping materials are widely used in industry to dampen the vibration and sounds of mechanical systems, such as automobiles, and appliances, such as washers and dryers, refrigerators, etc. Typically, vibration damping materials comprise thermoplastic or rubber materials which are capable of suppressing vibrations and sounds. The vibration damping materials are applied to selected parts or areas of the automobile or appliance to prevent vibrations and noise from being transmitted inside the automobile or outside the appliance.
A common method of applying the vibration damping material is to provide it in the form of a sheet or tape including an adhesive layer which adheres the damping material to the desired substrate, such as an automobile body panel or interior panel of an appliance. However, this requires that the vibration damping material be laminated to at least one pressure sensitive adhesive layer. Alternatively, the sheet or tape may be adhered to the substrate using mechanical fasteners. See, for example, U.S. Pat. Nos. 5,635,562, 5,712,038, and 5,858,521. However, the use of a separate adhesive layer or fastening materials adds additional steps and materials to the manufacturing process, which is both time-consuming and costly.
Accordingly, there is a need in the art for a vibration damping material tape which provides excellent vibration damping properties and which can be easily adhered to a substrate such as an automotive body panel or appliance wall without the need for separate adhesives or fasteners.
The present invention meets that need by providing a self-adhesive vibration damping tape which provides high bond adhesion to a substrate. In addition, the vibration damping tape of the present invention provides good vibration damping properties as well as sealing out the infiltration of air, dust and moisture.
According to one aspect of the present invention, a self-adhesive vibration damping tape is provided which comprises a vibration damping composition comprising a synthetic rubber polymer, a thermoplastic polymer selected from the group consisting of amorphous polyolefins and ethylene-based copolymers or terpolymers, a plasticizer, and an organic filler. The vibration damping composition is in the form of a tape having first and second major surfaces.
The synthetic rubber polymer is preferably selected from the group consisting of butyl rubber, polyisobutylene, and mixtures thereof.
In one embodiment of the invention, the thermoplastic polymer comprises an amorphous polyolefin selected from the group consisting of polypropylene-ethylene copolymers, polypropylene/polypropylene-ethylene copolymers, polypropylene homopolymers, polyethylene homopolymers, and mixtures thereof. In an alternative embodiment, the thermoplastic polymer comprises an ethylene-based copolymer or terpolymer selected from the group consisting of ethylene/vinyl acetate copolymers, ethylene/vinyl acetate/acid terpolymers, ethylene-acrylic acid copolymers, and mixtures thereof.
The plasticizer in the vibration damping composition preferably comprises polybutene.
The organic filler preferably comprises recycled automotive paint powder, which contributes to the vibration damping properties of the composition.
In a preferred embodiment of the invention, the self-adhesive vibration damping tape composition comprises from about 5 to 10% by weight of a synthetic rubber polymer; from about 1 to 10% by weight of a thermoplastic polymer selected from the group consisting of amorphous polyolefins and ethylene-based copolymers or terpolymers; from about 15 to 30% by weight of a plasticizer, and from about 5 to 50% by weight of an organic filler. More preferably, the composition comprises from about 23 to about 27% by weight of an organic filler.
The vibration damping composition may further include an antioxidant, an adhesion promoter, one or more coloring agents, dispersing agents, and conventional fillers such as inorganic fillers, reinforcing silicas, or desiccants.
In a preferred embodiment of the invention, a release liner is adhered to at least one major surface of the tape. An aluminum foil facing is also preferably laminated to at least one major surface of the tape. The facing preferably comprises aluminum foil, but may also comprise other metals, or plastics. Preferably, the release liner is adhered to one surface of the tape, and the aluminum foil facing is laminated to the other surface of the tape. The vibration damping tape (including the tape and facing) preferably has a thickness of about 0.5 to 2.0 mm.
In use, the self-adhesive vibration damping tape is adhered to a substrate such as an automotive or appliance part. The substrate may be comprised of a metal such as steel, or may also comprise wood, glass, or fabric. The tape is preferably adhered by removing the release liner such that the tape is adhered on its second surface to the substrate, such that the aluminum foil facing on its first surface faces outward. Once adhered, the tape/substrate composite exhibits a minimum composite loss factor of 0.05 at a temperature range of xe2x88x920xc2x0 C. to 60xc2x0 C. and resonance frequency of 200 Hz. By xe2x80x9ccomposite,xe2x80x9d it is meant the combination of the damping tape adhered to a substrate.
Accordingly, it is a feature of the present invention to provide a self-adhesive vibration damping composition which may be adhered to a substrate such as an automotive or appliance part. Other features and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.